Solid-state power interrupters

ABSTRACT

A power interrupter device includes a solid-state bidirectional switch and control circuitry to control the solid-state bidirectional switch. The bidirectional switch is connected between input and output terminals of the power interrupter device. The control circuitry includes driver circuitry and fault detection circuitry. The driver circuitry generates a regulated direct current (DC) voltage using current drawn from an input power source applied to the input terminal and applies the regulated DC voltage to a control input of the bidirectional switch. The fault detection circuitry is configured to sense a level of load current flowing in an electrical path between the input and output terminals, to detect an occurrence of a fault condition based on the sensed load current level, and to short the control input of the bidirectional switch to place the bidirectional switch in a switched-off state, in response to detecting the occurrence of a fault condition.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 16/029,549, filed on Jul. 7, 2018, the disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

This disclosure relates generally to power control systems and devicesand, in particular, solid-state power interrupter devices and fordisrupting power to loads.

BACKGROUND

Electrical power interrupters are an essential component in electricaldistribution systems and are often positioned between an incominghigh-current utility supply circuit and lower current branch circuitswithin a given building or home structure to protect branch circuitconductors and electrical loads from being exposed to over-currentconditions. There are several types of over current conditions includingoverload conditions and fault conditions. An overload condition isdefined as operation of equipment in excess of its normal, full-loadrating, or a branch circuit in excess of its ampacity which, when theoverload persists for a sufficient period of time, would cause damage ordangerous overheating. Fault conditions comprise unintended oraccidental load conditions that typically produce much higherover-current conditions than do overloads, depending on the impedance ofthe fault. A fault producing the maximum over-current condition isreferred to as a short-circuit or a “bolted fault.”

Conventional power interrupters are electromechanical in nature and haveelectrical contacts that are physically separated by either manualintervention of an operator lever or automatically upon the occurrenceof a fault condition or prolonged over current condition, in which casesthe circuit interrupter is deemed to be “tripped.” The separation of theelectrical contacts of a circuit breaker can be performedelectromagnetically or mechanically, or a combination of both. Asignificant problem with conventional circuit interrupters is that theyare slow to react to fault conditions due to their electromechanicalconstruction, and exhibit large variations in both the time to trip andthe current trip limit in response to a fault or prolonged over-currentconditions. Conventional power interrupters typically require at leastseveral milliseconds to isolate a fault condition. The slow reactiontime is undesirable since it raises the risk of hazardous fire, damageto electrical equipment, and arc-flashes, which can occur at theshort-circuit location when a bolted fault is not isolated quicklyenough.

SUMMARY

Embodiments of the disclosure include solid-state power interrupterdevices and methods for interrupting power from a source to a load. Forexample, an exemplary embodiment includes a power interrupter devicewhich comprises a solid-state bidirectional switch and controlcircuitry. The solid-state bidirectional switch is connected between aninput terminal and an output terminal of the power interrupter device.The control circuitry configured to control the solid-statebidirectional switch. The control circuitry comprises driver circuitryand fault detection circuitry. The driver circuitry is configured togenerate a regulated direct current (DC) voltage using current drawnfrom an input power source applied to the input terminal of the powerinterrupter device, and apply the regulated DC voltage to a controlinput of the solid-state bidirectional switch. The fault detectioncircuitry is configured to (i) sense a level of load current flowing inan electrical path between the input terminal and the output terminal ofthe power interrupter device, (ii) detect an occurrence of a faultcondition based on the sensed load current level, and (iii) short thecontrol input of the solid-state bidirectional switch to place thesolid-state bidirectional switch in a switched-off state, in response todetecting the occurrence of a fault condition.

Other embodiments will be described in the following detaileddescription of embodiments, which is to be read in conjunction with theaccompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a solid-state power interrupteraccording to an exemplary embodiment of the disclosure.

FIG. 2 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure.

FIG. 3 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure.

FIG. 4 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure.

FIG. 5 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure.

FIG. 6 schematically illustrates an AC-to-DC converter and regulatorcircuit according to an embodiment of the disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the disclosure will now be described in further detailwith regard to solid-state power interrupter devices and techniques forinterrupting power from a source to a load based on, e.g., a detectionof a fault condition (e.g., a short-circuit fault, an over-currentfault, etc.) or in response to external control signals. It is to beunderstood that same or similar reference numbers are used throughoutthe drawings to denote the same or similar features, elements, orstructures, and thus, a detailed explanation of the same or similarfeatures, elements, or structures will not be repeated for each of thedrawings. The term “exemplary” as used herein means “serving as anexample, instance, or illustration”. Any embodiment or design describedherein as “exemplary” is not to be construed as preferred oradvantageous over other embodiments or designs.

FIG. 1 schematically illustrates a solid-state power interrupteraccording to an exemplary embodiment of the disclosure. In particular,FIG. 1 illustrates a solid-state power interrupter 100 connected betweena utility power supply 10 (referred to herein as AC mains 10) and a load20 which is connected to a branch circuit that is protected by thesolid-state power interrupter 100. The solid-state power interrupter 100has input terminals that are connected to a hot phase 11 (referred to as“line hot L”) and a neutral phase 12 (referred to as “line neutral N”)of the AC mains 10, and output terminals that are connected a load hotline 21 and a load neutral line 22 of the load 20. In particular, thesolid-state power interrupter 100 comprises a line hot terminal 100A, aline neutral terminal 100B, a load hot terminal 100C, a load neutralterminal 100D (and optionally an earth ground terminal not shown). Theline hot terminal 100A is coupled to the line hot 11 of the AC mains 10,the line neutral terminal 100B is coupled to the line neutral 12 of theAC mains 10, the load hot terminal 100C is coupled to the load hot line21 of the load 20, and the load neutral terminal 100D is coupled to theneutral line 22 of the load 20. As further illustrated in FIG. 1, theline neutral 12 is shown bonded to earth ground 14 (GND), which providesadded protection as is known in the art. The earth ground 14 istypically connected to a ground bar in a circuit breaker distributionpanel, wherein the ground bar is bonded to a neutral bar in the circuitbreaker distribution panel.

The solid-state power interrupter 100 comprises a double pole singlethrow (DPST) switch circuit which comprises a first solid-state switch102, a second solid-state switch 104, and control circuitry 110 whichcomprises a first control circuit block 112, and a second controlcircuit block 114. In some embodiments, the first and second solid-stateswitches 102 and 104 comprise power MOSFET (metal-oxide semiconductorfield-effect transistor) devices and, in particular, N-type enhancementMOSFET devices having gate terminals (G), drain terminals (D), andsource terminals (S) as shown. The first and second solid-state switches102 and 104 (alternatively MOSFET switches 102 and 104) compriserespective intrinsic body diodes 102-1 and 104-1, which represent P-Njunctions between a P-type substrate body and N-doped drain regions ofthe MOSFET devices. In this regard, the body diodes 102-1 and 104-1 areintrinsic elements of the MOSFET switches 102 and 104 (i.e., notdiscrete elements). It is to be noted that the intrinsic body-to-sourcediodes of the first and second solid-state switches 102 and 104 are notshown as it is assumed that they are shorted out by connections betweenthe source regions and the substrate bodies (e.g., N+ source and P bodyjunction are shorted through source metallization).

The first solid-state switch 102 is serially connected in an electricalpath (referred to as “hot line path”) between the line hot terminal 100Aand the load hot terminal 100C of the solid-state interrupter 100. Thesecond solid-state switch 104 is serially connected in an electricalpath (referred to as “neutral line path”) between the line neutralterminal 100B and the load neutral terminal 100D of the solid-stateinterrupter 100. The first control circuit block 112 controls agate-to-source voltage (VGs) that is applied to the first solid-stateswitch 102 to control the activation and deactivation of the firstsolid-state switch 102. The second control circuit block 114 controls agate-to-source voltage that is applied to the second solid-state switch104 to control the activation and deactivation of the second solid-stateswitch 104. The first and second solid-state switches 102 and 104collectively comprise a solid-state bidirectional switch that isconfigured to enable bidirectional current flow between the AC mains 10and the load 20 (i.e., conduct positive current or negative current)when the first and second solid-state switches 102 and 104 are in aswitched-on state, and block current flow between the AC mains 10 andthe load 20 when the first and second solid-state switches 102 and 104are in a switched-off state.

More specifically, in normal operation of the solid-state powerinterrupter 100, during a positive half cycle of an AC supply voltagewaveform of the AC mains 10, a positive current flows in the hot linepath through the first solid-state switch 102, through the load 20, andthen in the neutral line path through the forward biased body diode104-1, and back to the AC mains 10. On the other hand, during a negativehalf cycle of the AC supply voltage waveform of the AC mains 10, anegative current flows in the neutral line path through the secondsolid-state switch 104, through the load 20, and then in the hot linepath through the forward biased body diode 102-1, and back to the ACmains 10. The exemplary configuration of simultaneously controlling ACswitches on both the line and the neutral is referred to as double-poleswitching and is applied to the two lines (hot and neural lines) ofopposite phase from the single AC energy source.

The control circuitry 110 implements various functions for controllingthe activation and deactivation of the first and second solid-stateswitches 102 and 104. For example, in some embodiments, the controlcircuitry 110 comprises self-biasing driver circuitry which isconfigured to utilize AC power from the AC mains 10 to generateregulated DC voltages to drive the gate terminals of the first andsecond solid-state switches 102 and 104. Further, in some embodiments,the control circuitry 110 comprises fault detection circuitry which isconfigured to sense an amount of load current flowing in the hot linepath and/or the neutral line path through the solid-state interrupter100, and detect an occurrence of a fault condition, such asshort-circuit fault, an over-current fault, etc., based on the sensedcurrent level. In response to detecting a fault condition, the faultdetection circuitry is configured to short the control input (e.g., gateterminal) of at least one of the solid-state switches 102 and 104 tointerrupt power to the load 20.

Furthermore, in some embodiments, the control circuitry 110 comprises acontrol switch to implement a forced turn-off control mode in which thesolid-state power interrupter 100 is controlled by external controlsignals. For example, in some embodiments, the control circuitry 110implements an optical switch which is configured to short the controlinputs of the first and second solid-state switches 102 and 104 to placethe first and second solid-state switches 102 and 104 in a switched-offstate, in response to an optical control signal applied to the opticalswitch. In some embodiments, the control circuitry 110 implements aforced turn-off control mode in which the first and second solid-stateswitches 102 and 104 are turned-off in response to the detection ofcertain events including, but not limited to, detection of fault events,detection of hazardous environmental conditions, remote commands forcircuit interruption, etc. As explained in further detail below, theforced turn-off control mode can be initiated on command by, e.g.,direct hardware fault sensing and control, and/or through a galvanicallyisolated control input based on, but not limited to, optical, magnetic,capacitive, and RF isolation technologies.

FIG. 2 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure. Inparticular, FIG. 2 schematically illustrates a solid-state powerinterrupter 200 which is similar to the solid-state power interrupter100 of FIG. 1, except that the solid-state power interrupter 200 furthercomprises isolation circuitry 210 to provide galvanic isolation betweenthe solid-state power interrupter 200 and the load 20 when the first andsecond solid-state switches 102 and 104 are turned off In someembodiments, the isolation circuitry 210 is connected across the loadhot terminal 100C and the load neutral terminal 100D. The isolationcircuitry 210 is configured to shunt the load 20 from unwanted leakagecurrent flow from the AC mains 10 though the switched-off solid-stateswitches 102 and 104. When the first and second solid-state switches 102and 104 are turned-off, the first and second solid-state switches 102and 104 can generate a small amount of leakage current. For example,when the first and second solid-state switches 102 and 104 are in aswitched-off state (e.g., cutoff mode), a small amount of leakagecurrent (e.g., 200 uA) can flow through the first and second solid-stateswitches 102 and 104 and generate a sizable voltage drop across the load20 when the load 20 comprises a high impedance load. In this regard,when activated, the isolation circuitry 210 provides a short circuitbetween the load hot terminal 100C and the load neutral terminal 100D toshunt the load 20 from any unwanted leakage current flow though theswitched-off solid-state switches 102 and 104.

In some embodiments, the isolation circuitry 210 comprises a controlcircuit 220, a solid-state bidirectional switch comprising MOSFETswitches 222 and 224 and associated body diodes 222-1 and 224-1. Whenthe first and second solid-state switches 102 and 104 are turned off,the control circuit 220 generates gate control voltages to activate theMOSFET switches 222 and 224, and thereby create a short circuit pathbetween the load hot terminal 100C and the load neutral terminal 100D,which allows any leakage current from the deactivated first and secondsolid-state switches 102 and 104 to flow through the isolation circuitry210, and thereby shunt the unwanted leakage to prevent such leakagecurrent from flowing into the load 20. The effect of bypassing orshunting leakage current away from the load 20 serves to isolate (e.g.,galvanically isolate) the load 120 from the solid-state powerinterrupter 200 when the first and second switches 102 and 104 are in aswitched-off state in a way that is equivalent to a galvanic isolationtechnique which implements an air-gap between the AC mains 10 and theload 20. In this configuration, the isolation circuitry 210 serves as apseudo air-gap.

FIG. 3 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure. Inparticular, FIG. 3 schematically illustrates a solid-state powerinterrupter 300 comprising a single pole single throw (SPST) switchframework in which the first solid-state switch 102 and the secondsolid-state switch 104 are serially connected in the hot line pathbetween the line hot terminal 100A and the load hot terminal 100C,thereby providing a solid-state bidirectional switch disposed in the hotline path of the solid-state power interrupter 300. The solid-statepower interrupter 300 further comprises control circuitry 310 toimplement an exemplary embodiment of the control circuitry 110 andassociated functions (e.g., self-biasing driver circuitry, faultdetection circuitry, force-turn off control circuitry) as discussedabove in conjunction with FIG. 1.

For example, as schematically illustrated in FIG. 3, the controlcircuitry 310 comprises a current sense resistor 312, an operationalamplifier 314, a first control switch 316, a second control switch 318,a first diode 320, a second diode 322, a first resistor 324, a secondresistor 326, a third resistor 328, a Zener diode 330, and a capacitor332. In some embodiments, the first and second diodes 320 and 322, theresistors 324, 326, and 328, the Zener diode 330, and the capacitor 332collectively implement self-biasing driver circuitry that is configuredto utilize AC power from the AC mains 10 to generate a regulated DCvoltage at an internal node N1 to drive the control inputs (e.g., gateterminals) of the first and second solid-state switches 102 and 104 andthereby activate the first and second solid-state switches 102 and 104.

As schematically illustrated in FIG. 3, the first diode 320 and thefirst resistor 324 are serially connected between the hot line path(e.g., the line hot terminal 100A node) and the internal node N1. Inaddition, the second diode 322 and the second resistor 326 are seriallyconnected between the neutral line path (e.g., the line neutral terminal100B node) and the internal node N1. In operation, during a negativehalf cycle of the AC supply voltage waveform of the AC mains 10, thesecond diode 322 is activated, and current flows from the line neutral12 to the line hot 11 through the second diode 322, the second resistor326, the capacitor 332, and the body diode 102-1 of the firstsolid-state switch 102. This current flow causes a voltage across thecapacitor 332 to increase until the capacitor voltage reaches a clampingvoltage (i.e., Zener voltage) of the Zener diode 330. In other words,the Zener voltage of the Zener diode 330 limits the maximum level of theself-bias turn-on threshold voltage (VGs) which is generated on theinternal node N1 to turn on the first and second solid-state switches102 and 104.

In this exemplary embodiment, the voltage level on the internal node N1is limited by the Zener voltage (i.e., reverse breakdown voltage) of theZener diode 330 such that the Zener diode 330 serves as a solid-stateclamp to limit the driving voltage on the internal node N1 to drive thecontrol inputs (e.g., gate terminals) of the first and secondsolid-state switches 102 and 104. In this regard, the self-bias drivingvoltage is input-line voltage independent, as the level of the self-biasdriving voltage is limited by the solid-state clamp. During a positivehalf cycle of AC supply voltage waveform of the AC mains 10, the firstdiode 320 is activated, and current flows from the line hot 11 to theline neutral 12 through the first diode 320, the first resistor 324, thecapacitor 332, and the body diode 104-1 of the second solid-state switch104. This current flow causes charge to trickle across the Zener diode330 to maintain the regulated DC voltage (i.e., the Zener voltage) onthe internal node N1 for driving the control terminal of the first andsecond solid-state switches 102 and 104.

Further, in some embodiments, the current sense resistor 312, theoperational amplifier 314, and the first control switch 316 collectivelycomprise a fault detection circuit of the control circuitry 310. Thefault detection circuit is configured to (i) sense an amount of loadcurrent flowing in the hot line path through the solid-state interrupter100, (ii) detect an occurrence of a fault condition, such asshort-circuit fault, an over-current fault, etc., based on the sensedcurrent level, and (iii) in response to detecting the fault condition,shunt the control inputs (e.g., gate terminals) of the first and secondsolid-state switches 102 and 104 to thereby deactivate the first andsecond solid-state switches 102 and 104 and interrupt power to the load20.

As schematically illustrated in FIG. 3, the sense resistor 312 isserially connected between the source terminals (S) (e.g., between nodesN2 and N3) of the first and second solid-state switches 102 and 104. Theoperational amplifier 314 comprises first and second input terminals(e.g., differential input terminals) which are connected to the nodes N2and N3 across the sense resistor 312. The operational amplifier 314comprises an output terminal that is connected to the first controlswitch 316. In some embodiments, the first control switch 316 comprisesa bipolar junction transistor (BJT) device having a base terminalconnected to the output terminal of the operational amplifier 314, anemitter terminal connected to the node N3, and a collector terminalconnected to the gate terminals of the first and second solid-stateswitches 102 and 104.

During operation, the sense resistor 312 generates a burden voltage orsense voltage as a result of load current flowing in the hot line paththrough the sense resistor 312. The sense voltage is applied to thedifferential inputs of the operational amplifier 314, and theoperational amplifier 314 amplifies the sense voltage to generate anoutput voltage that is applied to the base terminal of the first controlswitch 316. When the output voltage of operational amplifier 314 is highenough (e.g., base-emitter voltage VBE is about 0.7 V), the firstcontrol switch 316 will turn on, which shunts the gate and sourceterminals of the first and second solid-state switches 102 and 104, andthereby causes the first and second solid-state switches 102 and 104 toturn off and interrupt power to the load 20.

In some embodiments, the sense resistor 312 has a very small resistancevalue such as on the order of 1 milliohm or less (e.g., 10× less than 1milliohm). In this regard, the sense voltage across the sense resistors312 is negligible in terms of causing minimal power dissipation, but yetsufficient for current sensing. The operational amplifier 314 isconfigured to have sufficient gain to be able to drive the first controlswitch 316, even with a relatively small voltage input corresponding tothe voltage drop across the sense resistor 312. In this regard, theresistance value of the sense resistor 312 and the gain of theoperational amplifier 314 are selected for a target load current limit(e.g., 100 amperes) to ensure that the output of the operationalamplifier 314 generates a sufficient voltage to turn on the firstcontrol switch 316 when the magnitude of load current that flows throughthe sense resistor 312 reaches or exceeds the target current limit. Inother words, the sense resistor 312 can have a relatively smallresistance value (e.g., 1 milliohm) which generates a relatively smallsense voltage and minimizes power dissipation for normal circuitoperation, but which is amplified by the operational amplifier 314 toenable over-current detection using the small sense voltage. Moreover,the resistance value of the sense resistor 312 can remain fixed (e.g., 1milliohm) while the gain of the operational amplifier 314 is adjusted asdesired to adjust the target load current level for over-current andshort circuit detection.

Furthermore, in some embodiments, the control circuitry 310 includes thesecond control switch 318 to implement a forced turn-off control circuitin which the solid-state power interrupter 300 is controlled by acontrol signal 318-s (e.g., optical signal) which is generated by, e.g.,an external control system or device. In particular, the second controlswitch 318 is activated in response to the control signal 318-s, whereinactivation of the second control switch 318 serves to shunt the gate andsource terminals of the first and second solid-state switches 102 and104, which thereby causes the first and second solid-state switches 102and 104 to turn off and interrupt power to the load 20.

In some embodiments, the second control switch 318 comprises aphototransistor (e.g., an optical BJT device which includes a photodiodejunction) or other types of optically controlled switches which receiveoptical signals from complementary light emitting diodes (LED) that arecontrolled by, e.g., a sensor device or a microcontroller. The controlsignal 318-s can be generated in response to remote commands (e.g.,alarm signals) received from a local or a remote controller that isconfigured to detect fault conditions, or in response to remote commandsreceived from an individual who can control operation of the solid-statepower interrupter 300 through smart technologies implemented using, forexample, an Internet-of-Things (IoT) wireless computing network, whereinthe solid-state power interrupter 300 comprises a smart wireless IoTdevice.

In some embodiments, the control signal 318-s is generated in responseto the detection of hazardous environmental conditions by one or moresensors that are configured to sense environmental conditions. Forexample, such sensors can include one or more of (i) a chemicalsensitive detector that is configured to detect the presence ofhazardous chemicals, (ii) a gas sensitive detector that is configured todetect the presence of hazardous gases, (iii) a temperature sensor thatis configured to detect high temperatures indicative of, e.g., a fire,(iv) a piezoelectric detector that is configured to detect largevibrations associated with, e.g., explosions, earthquakes, etc., (v) ahumidity sensor or water sensor that is configured to detect floods ordamp conditions, and other types of sensors that are configured todetect for the presence or occurrence of hazardous environmentalconditions that would warrant power interruption to the load 20.

In some embodiments, the control signal 318-s comprises ambient lightthat is sensed by the second control switch 318 which operates as alight sensor when implemented as a phototransistor. In this instance,the solid-state power interrupter 300 can be a component of anelectrical light switch device such that when the intensity of theambient light (e.g., intensity of the optical signal 318-3) reaches acertain level, the second control switch 318 is activated to turn offthe first and second solid-state switches 102 and 104 an interrupt powerthat is delivered to a lighting element.

The optical coupling between second control switch 318 and the externalcontrol system which control the generation of the control signal 318-sessentially provides galvanic isolation between the solid-state powerinterrupter 300 and the external control system. In other embodiments,galvanic isolation can be implemented using magnetic, capacitive, orradio frequency (RF) isolation technologies.

FIG. 4 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure. Inparticular, FIG. 4 schematically illustrates a solid-state powerinterrupter 400 which is similar to the solid-state power interrupter300 of FIG. 3, except the solid-state power interrupter 400 comprisesthe second solid-state switch 104 serially connected in the neutral linepath between the line neutral terminal 100B and the load neutralterminal 100D of the solid-state interrupter 400 (similar to theexemplary embodiment of FIG. 1). In addition, the solid-state powerinterrupter 400 comprises control circuitry 410 which is similar to thecontrol circuitry 310 the solid-state power interrupter 300 of FIG. 3,except that the control circuitry 410 further comprises an additionalresistor 428, Zener diode 430, and capacitor 432 to implement a separateself-biasing driver circuit that is configured to utilize AC power fromthe AC mains 10 to generate a regulated DC voltage (e.g., turn-onthreshold voltage) at an internal node N4 to drive the gate terminal ofsecond solid-state switch 104.

Similar to the operation of the control circuitry 310 of FIG. 3, duringa negative half cycle of the AC supply voltage waveform of the AC mains10, the second diode 322 is activated, and current flows from the lineneutral 12 to the line hot 11 through the second diode 322, the secondresistor 326, the capacitor 332, and the body diode 102-1 of the firstsolid-state switch 102. This current flow causes a voltage across thecapacitor 332 to increase until the capacitor voltage reaches the Zenervoltage of the Zener diode 330, whereby the Zener diode 330 serves as asolid-state clamp to limit the level of the regulated DC voltage that ismaintained on the internal node N1 to drive the first solid-state switch102.

On the other hand, during a positive half cycle of AC supply voltagewaveform of the AC mains 10, the first diode 320 is activated, andcurrent flows from the line hot 11 to the line neutral 12 through thefirst diode 320, the first resistor 324, the capacitor 332, and the bodydiode 104-1 of the second solid-state switch 104. This current flowcauses a voltage across the capacitor 432 to increase until thecapacitor voltage reaches the Zener voltage of the Zener diode 430,whereby the Zener diode 430 serves as a solid-state clamp to limit thelevel of the regulated DC voltage that is maintained on the internalnode N4 to drive the second solid-state switch 104.

Furthermore, while not specifically shown in FIG. 4, a second faultdetection circuit block and a second forced turn-off control circuitblock (which comprise the same components, circuit connections, andfunctionalities as the current sense resistor 312, the operationalamplifier 314, and the first and second control switches 316 and 318)can be implemented on the neutral line path to provide a separate faultdetection block for sensing load current flowing on the neutral linepath, and to implement a forced turn-off control of the secondsolid-state switch 104, using the same techniques as discussed above inconjunction with FIG. 3.

FIG. 5 schematically illustrates a solid-state power interrupteraccording to another exemplary embodiment of the disclosure. Inparticular, FIG. 5 schematically illustrates a solid-state powerinterrupter 500 which is similar to the solid-state power interrupter400 of FIG. 4, except that the solid-state power interrupter 500implements a different circuit configuration of the fault detectioncircuitry. In particular, as schematically illustrated in FIG. 5, thefault detection circuitry comprises a current sense resistor 512 and thefirst control switch 316, which are configured to (i) sense an amount ofload current flowing in the hot line path through the solid-stateinterrupter 100, (ii) detect an occurrence of a fault condition, such asshort-circuit fault, an over-current fault, etc., based on the sensedcurrent level, and (iii) in response to detecting a fault condition,shunt the control input of the first solid-state switch 102 to therebydeactivate the first solid-state switch 102 and interrupt power to theload 20.

As schematically illustrated in FIG. 5, the sense resistor 512 isserially connected between the source terminals (S) (e.g., between nodesN2 and N3) of the first and second solid-state switches 102 and 104. Inaddition, the base terminal of the first control switch 316 (BJT device)is connected to the node N2, and the emitter terminal of the firstcontrol switch 316 is connected to the node N3. In this configuration,during operation, the sense resistor 512 generates a burden voltage orsense voltage as a result of load current flowing in the hot line paththrough the sense resistor 512. When the sense voltage is high enough(e.g., base-emitter voltage VBE is about 0.7 V), the first controlswitch 316 will turn on, which shunts the gate and source terminal ofthe first solid-state switch 102, and thereby causes the firstsolid-state switch 102 to turn off and interrupt power to the load 20.

In some embodiments, the sense resistor 512 has a resistance value thatis selected for a target load current limit (e.g., 100 amperes) toensure that the first control switch 316 is activated when the magnitudeof the load current that flows through the sense resistor 512 reaches orexceeds the target load current limit. For example, assuming that thefirst control switch 316 is activated when the base-emitter voltage VBEreaches 0.7 V, and assuming that the load current limit is selected tobe 100 amperes, the sense resistor would have a resistance of 0.007 ohms(i.e., V=IR, where 0.7 V=100 A×0.007 ohms).

Furthermore, while not specifically shown in FIG. 5, a second faultdetection circuit block and a second forced turn-off control circuitblock (which comprise the same components, circuit connections, andfunctionalities as the current sense resistor 512, and the first andsecond control switches 316 and 318) can be implemented on the neutralline path to provide a separate fault detection block for sensing loadcurrent flowing on the neutral line path, and to implement a forcedturn-off control of the second solid-state switch 104, using the sametechniques as discussed above.

As further shown in FIG. 5, the solid-state power interrupter 500further comprises isolation circuitry 520, which is connected across theload hot terminal 100C and the load neutral terminal 100D, to providegalvanic isolation between the solid-state power interrupter 500 and theload 20 when the solid-state switches 102 and 104 are turned off. Insome embodiments, the isolation circuitry 520 implements the isolationcircuitry 210 shown in FIG. 2. It is to be understood that the isolationcircuitry 210 of FIG. 2 can be implemented in the exemplary embodimentsof the solid-state power interrupters 300 and 400 shown in FIGS. 3 and4.

FIG. 6 schematically illustrates an AC-to-DC converter and regulatorcircuit according to an embodiment of the disclosure. In particular,FIG. 6 schematically illustrates an AC-to-DC converter and regulatorcircuit 600 which has a circuit framework that is based on theself-biasing driver circuitry of the solid-state power interrupter 500of FIG. 5. The AC-to-DC converter and regulator circuit 600 isconfigured to utilize AC power from the AC mains 10 to generate tworegulated DC voltages V_(DC) 1 and V_(DC) 2 at nodes N1 and N2,respectively. In FIG. 5, the regulated DC voltages V_(DC) 1 and V_(DC) 2are utilized to drive the gate terminals of the respective first andsecond solid-state switches 102 and 104. However, the AC-to-DC converterand regulator circuit 600 can be implemented in other applications togenerate regulated DC voltages from AC power.

As shown in FIG. 6, the AC-to-DC converter and regulator circuit 600comprises discrete diodes 602 and 604, which correspond to the parasiticbody diodes 102-1 and 104-1, respectively, in FIG. 5. The AC-to-DCconverter and regulator circuit 600 further comprises a first clampingcircuit block comprising a first Zener diode 610 and a first capacitor612 connected to the first node N1, and a second clamping circuit blockcomprising a second Zener diode 614 and a second capacitor 616 connectedto the second node N2. The AC-to-DC converter and regulator circuit 600further comprises a diode 620 and resistor 622 serially connectedbetween an AC line input terminal 600A and the second node N2, and adiode 624 and resistor 626 serially connected between an AC neutral lineinput terminal 600B and the first node N1.

During a negative half cycle of an AC supply voltage waveform of the ACmains 10, the diodes 624 and 604 are activated, and current flows fromthe line neutral 12 to the line hot 11 through the diode 624, theresistor 626, the first capacitor 612, and the diode 602. This currentflow causes a voltage across the first capacitor 612 to increase untilthe capacitor voltage reaches a Zener voltage of the first Zener diode610. In this regard, the first Zener diode 610 serves as a solid-stateclamp to limit the level of the regulated DC voltage V_(DC) 1 that ismaintained on the first node N1. On the other hand, during a positivehalf cycle of AC supply voltage waveform of the AC mains 10, the diodes620 and 604 are activated, and current flows from the line hot 11 to theline neutral 12 through the diode 620, the resistor 622, the secondcapacitor 616, and the diode 604. This current flow causes a voltageacross the second capacitor 616 to increase until the capacitor voltagereaches the Zener voltage of the second Zener diode 614. In this regard,the second Zener diode 614 serves as a solid-state clamp to limit thelevel of the regulated DC voltage V_(DC) 2 that is maintained on thesecond node N2.

Exemplary embodiments of the disclosure as shown in FIGS. 1, 2, 3, 4,and 5 include novel architectures for solid-state power interrupterdevices that can be disposed between an input energy source and anoutput load. While the exemplary solid-state power interrupters aregenerically depicted as connecting the AC mains 10 to a load 20, it isto be understood that the exemplary power interrupters can be embodiedin various devices and applications. For example, in some embodiments,the power interrupters shown in FIGS. 1-5 can be implemented in anelectrical circuit breaker device (e.g., intelligent circuit breakerdevice), which is disposed in a circuit breaker distribution panel. Inaddition, in some embodiments, the power interrupters shown in FIGS. 1-5can be implemented in an electrical receptacle device, or an electricallight switch (e.g., a wall-mounted light switch or a light switchimplemented in a smart light fixture or smart ceiling light bulb socket,etc.). In other embodiments, the power interrupters shown in FIGS. 1-5may comprise standalone devices that can be disposed within a gang boxin an electrical network of a home or building and configured to protectone or more electrical devices, appliances, loads, etc., that areconnected in a branch circuit downstream of the standalone powerinterrupter device.

Although exemplary embodiments have been described herein with referenceto the accompanying figures, it is to be understood that the inventionis not limited to those precise embodiments, and that various otherchanges and modifications may be made therein by one skilled in the artwithout departing from the scope of the appended claims.

What is claimed is:
 1. A power interrupter device, comprising: asolid-state bidirectional switch connected between an input terminal andan output terminal of the power interrupter device; and controlcircuitry configured to control the solid-state bidirectional switch,wherein the control circuitry comprises: driver circuitry configured togenerate a regulated direct current (DC) voltage using current drawnfrom an input power source applied to the input terminal of the powerinterrupter device, and apply the regulated DC voltage to a controlinput of the solid-state bidirectional switch; and fault detectioncircuitry configured to (i) sense a level of load current flowing in anelectrical path between the input terminal and the output terminal ofthe power interrupter device, (ii) detect an occurrence of a faultcondition based on the sensed load current level, and (iii) short thecontrol input of the solid-state bidirectional switch to place thesolid-state bidirectional switch in a switched-off state, in response todetecting the occurrence of a fault condition.
 2. The power interrupterdevice of claim 1, wherein the driver circuitry comprises voltageclamping circuit, wherein the voltage clamping circuit is configured togenerate the regulated DC voltage, wherein the voltage clamping circuitcomprises a capacitor and a Zener diode connected in parallel, whereinthe regulated DC voltage comprises a Zener voltage of the Zener diode.3. The power interrupter device of claim 1, wherein the fault detectioncircuitry comprises: a current sense resistor serially connected betweena first node and a second node in an electrical path between the inputterminal and the output terminal of the power interrupter device; anoperational amplifier comprising differential input terminals connectedto the first and second nodes across the sense resistor; and a firstcontrol switch having a control input connected to an output of theoperational amplifier.
 4. The power interrupter device of claim 3,wherein the current sense resistor comprises a resistance that is nogreater than about one milliohm.
 5. The power interrupter device ofclaim 3, wherein the first control switch comprises bipolar junctiontransistor (BJT) device having a base terminal connected to the outputterminal of the operational amplifier, an emitter terminal connected tothe second node in the electrical path between the input terminal andthe output terminal of the power interrupter device, and a collectorterminal connected to the control input of the solid-state bidirectionalswitch.
 6. The power interrupter device of claim 1, wherein the faultdetection circuitry comprises: a current sense resistor seriallyconnected between a first node and a second node in an electrical pathbetween the input terminal and the output terminal of the powerinterrupter device; a first control switch having a first terminalconnected the first node in the electrical path, a second terminalconnected to the second node in the electrical path, and a thirdterminal connected to connected to the control input of the solid-statebidirectional switch.
 7. The power interrupter device of claim 6,wherein the first control switch comprises bipolar junction transistor(BJT) device having a base terminal connected to the first node, anemitter terminal connected to the second node, and a collector terminalconnected to the control input of the solid-state bidirectional switch.8. The power interrupter device of claim 1, wherein the controlcircuitry further comprises a forced turn-off control circuit configuredto (i) receive an external control signal and (ii) short the controlinput of the solid-state bidirectional switch to place the solid-statebidirectional switch in a switched-off state, in response to theexternal control signal.
 9. The power interrupter device of claim 8,wherein the forced turn-off control circuit comprises a second controlswitch having a first control terminal configured to receive theexternal control signal, a second terminal connected to a node in anelectrical path between the input terminal and the output terminal ofthe power interrupter device, and a third terminal connected to thecontrol input of the solid-state bidirectional switch.
 10. The powerinterrupter device of claim 9, wherein the second control switchcomprises a phototransistor device having a base terminal configure toreceive an optical control signal, an emitter terminal connected to thenode in the electrical path, and a collector terminal connected to thecontrol input of the solid-state bidirectional switch.
 11. The powerinterrupter device of claim 1, further comprising an isolation circuitwhich is configured to shunt leakage current from a load circuitconnected to the circuit interrupter, when the solid-state bidirectionalswitch is in a switched-off state.
 12. The power interrupter device ofclaim 1, wherein the solid-state bidirectional switch comprises a firstMOSFET switch and a second MOSFET switch.
 13. The power interrupterdevice of claim 12, wherein the solid-state bidirectional switch isimplemented in a double pole single throw configuration wherein thefirst MOSFET switch is connected in a hot line path between a first lineinput terminal and an a first load output terminal of the powerinterrupter device, and the second MOSFET switch is connected in aneutral line path between a second line input terminal and a second loadoutput terminal of the power interrupter device.
 14. The powerinterrupter device of claim 12, wherein the solid-state bidirectionalswitch is implemented in a single pole single throw configurationwherein the first and second MOSFET switches are serially connected in ahot line path between a first line input terminal and a first loadoutput terminal of the power interrupter device.
 15. A methodcomprising: controlling a solid-state bidirectional switch, which isconnected between an input terminal and an output terminal of the powerinterrupter device, to place the solid-state bidirectional switch in oneof (i) a switched-on state to provide an electrical connection in anelectrical path between the input terminal and the output terminal, and(ii) a switched-off state; wherein controlling the solid-statebidirectional switch comprises: generating a regulated direct current(DC) voltage using current drawn from an input power source applied tothe input terminal of the power interrupter device, and applying theregulated DC voltage to a control input of the solid-state bidirectionalswitch; and detecting for a fault condition by (i) sensing a level ofload current flowing in an electrical path between the input terminaland the output terminal of the power interrupter device, (iii) detectingan occurrence of a fault condition based on the sensed load currentlevel, and (iii) shorting the control input of the solid-statebidirectional switch to place the solid-state bidirectional switch in aswitched-off state, in response to detecting the occurrence of a faultcondition.
 16. The method of claim 15, wherein generating the regulatedDC voltage comprises applying current drawn from the input power sourceto charge a capacitor to a Zener voltage of a Zener diode connected inparallel with the capacitor, wherein the regulated DC voltage comprisesthe Zener voltage of the Zener diode.
 17. The method of claim 15,wherein: sensing the level of load current flowing in the electricalpath between the input terminal and the output terminal comprisessensing a voltage that is generated by a current sense resistor inresponse to the load current flowing in the electrical path through thecurrent sense resistor; and detecting for the occurrence of a faultcondition based on the sensed load current level, and shorting thecontrol input of the solid-state bidirectional switch to place thesolid-state bidirectional switch in a switched-off state, in responsedetecting the occurrence of a fault condition comprises: amplifying thesensed voltage to generate an amplified voltage; applying the amplifiedvoltage to a control input of a first control switch; and activating thefirst control switch in response to the amplified voltage, whereinactivation of the first control switch causes the shorting of thecontrol input of the solid-state bidirectional switch.
 18. The method ofclaim 15, further comprising: applying an optical control signal toactivate an optical switch of the circuit interrupter; and shorting thecontrol input of the solid-state bidirectional switch to place thesolid-state switch in the switched-off state, in response the activationof the optical switch.
 19. An AC-to-DC converter and regulator circuit,comprising: a hot line input terminal and a neutral line input terminalconfigured for connection to an AC power source; a first diode and afirst resistor serially connected between the hot line input terminaland a first node; a second diode and a second resistor seriallyconnected between the neutral line input terminal and a second node; afirst clamping circuit coupled between the first node and the neutralline input terminal, wherein the first clamping circuit comprises afirst Zener diode and a first capacitor; a second clamping circuitcoupled between the second node and the hot line input terminal, whereinthe second clamping circuit comprises a second Zener diode and a secondcapacitor; a third diode connected between the line hot terminal and thesecond clamping circuit; and a fourth diode connected between the lineneutral terminal and the first clamping circuit.
 20. The AC-to-DCconverter and regulator circuit of claim 10, wherein: wherein inresponse to a positive half cycle of an AC supply voltage waveformapplied to the hot line and neural line input terminal, the first andforth diodes are activated, and a first current flows from the line hotterminal through the first diode, the first resistor, the firstcapacitor, and the fourth diode, wherein the first current increases avoltage across the first capacitor to a first Zener voltage of the firstZener diode; and wherein in response to a negative half cycle of the ACsupply voltage waveform applied to the hot line and neural line inputterminal, the second and third diodes are activated, and a secondcurrent flows from the line neutral terminal through the second diode,the second resistor, the second capacitor, and the third diode, whereinthe second current increases a voltage across the second capacitor to asecond Zener voltage of the second Zener diode; wherein the first Zenervoltage comprises a first regulated DC voltage on the first node; andwherein the second Zener voltage comprises a second regulated DC voltageon the second node.